Air-pump



C. E. ANDERSON. Am PUMP.

APPLICATION FILED NOV.13, 1919.

Patented Nov. 1. 1921.

UNITED STATES CARI E. ANDERSON, 0F MAYWOOI), ILLINOIS.

AIR-PUMP.

Specication of Letters Patent.

Patented Nov. 1, 1921.

Application led November 13, 1919. Serial No. 337,682.

To all whom z't may concern.'

Beit known that I, CARL E. ANDERSON, a citizen of the United States, residing at Maywood, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in Air-Pumps, of which the following is a description, reference being had to the accompanying drawing and to the figures of reference marked thereon.

The invention relates to new and useful improvements in air pumps, andl more particularly to a rotating Agear air pump which may be used for compressing air or for producing a vacuum in a chamber.

Y In pumps of the above character, it is essential that the teeth of the pumping gears shall run in very accurate Contact with the wall of the pump chamber, and an object of the present invention is to provide an efiicient lubricating means for lubricating this inner wall of the pump chamber in which the gears rotate.

A further object of the invention is to provide means whereby the oil which is lused for lubricating the pumping ars may be collected at the compression si e ofthe pump and returned to 'the receiving or vacuum side of the pum for re-use 1n connection with the lubricatlng of the gears.

A still further object of the invention is to provide a lubricating means wherein the lubricating oil, in relatively small quantities, is mixed with the air passing through the pump for lubricating the pumping gears, and wherein the discharge of the air into the compression chamber is well above the surface of the lubricating oil accumulatingtherein.

A still further object of the invention is to provide a. pump of the above character wherein means is provided for slowly returning the oil in the compression chamber to the vacuum chamber whereby it may be( again taken up by the incoming air and used for lubricating purposes.

These and other objects will in part be obvious and will in part be hereinafter more fully described.

In the drawings which show by way of illustration, andv more or less diagrammatically, one embodiment of the invention Figure 1 is a vertical sectional view through the pump embodying my improvements, and

Fig. 2 is a sectional view on the line 2-2 OfiFg. 1.

The invention broadly is directed' to an air pump having intermeshing rotary gear pumping members which are mountedto rotate in pump chambers so constructed that the teeth of the pumping gears make very accurate running' contact with the wall of the pump chambers. At one side of the pumpin members is a-vacuum chamber, and at t e other side is a compression chamber. Ports are provided so that air is drawn from the vacuum chamber by the rotation of the pumping members and delivered to the compression chamber. Extending downwardly into the vacuum chamber is a pipe which is connected with the receiving air intake port. This pipe extends to a point near the bottom of the vacuum chamber. Also at the delivery side of the pump there is a pipe which extends well up into the compression chamber, Land is preferably curved so as to deliver the air in a downward direction into the compression chamber;A

With this. arrangement of parts, when oil is placed inthe vacuum chamber, it will be taken up by the air and carried through into the compression chamber, and will thoroughly lubricate the inner wall of the pump chamber with which the teeth of the pum/ping gears make contact. A bypass is provided for allowing the oil to run slowly from the compression chamber into the vacuum chamber, and thus a complete cycle is rovided whereby a very small portion of ll)ubricating oil is taken up with the incoming air carried through the, pumping chamber into contact with the wall thereof and into the compression chamber, thence back through the bypass tothe vacuum chamber. The bypass leads into the compression chamber at a point below the normal surface of the oil therein and is very small, so that it runs more slowly through the bypass into the vacuum chamber than the capacity of the pump for carrying oil and air from the vacuum chamber into the compression chamber;

Referring more in detail to the drawings,

of the pump casing is closed by a base piece 3 which has a threaded connection with the cylindrical body portion at 4 and a suitable packing 5 is inserted for making an airtight joint between the body portion of the casing and the base. The casing is provided with a central section 6 which is formed with a cylindrical bore 7 to receive a cylindrical body portion 8. This body portion 8 is formed with two pump chambers'9 and 10. In the pump chamber 9 is a rotating pumping gear 11 and in the pump chamber 10 is a rotatingj pumping gear 12. These chambers are very accurately formed so that the teeth of the pumping gears make very close running contact with their respective pumping chambers. This is essential in order that the rotating gears may draw the air from the vacuum chamber and deliver the same into the compression chamber. The gears intermesh in the usual well lmown way. Said gears are rotated in the direction of the arrow as indicated in 1. The pumping gear 11 is mounted on a suitable shaft 13, and the pumping gear 12 is mounted on a suitable shaft 14. At the inner end of the bore 7 is a bearing plate 15 which is provided with suitable bearings for the inner ends of the shafts 13 and 14, respectively. The bore 7 in the plate 16 which is also provided with suitable bearings for the outer ends of the shafts 13 and 14', respectively. Said cover plate has an extension 17, and the shaft 13 extends outwardly through this extension 17 as indicated at 18. A nut 19 extends over the projecting end 18 of the shaft, and a packing 20 forced by the nut into contact with the shaft serves to insure a tight joint to prevent air from escaping along the'shaft 18. The cover plate 16 is Securedto the pump casing by suitable bolts- 21, and a packlng 22 foJnns an airtight connection between the cover plate and the body portion of the pump casing.

The section 6 containin the bore .7 extends downwardly in the s apeof a pipe as indicated at 23. This pipe extension terF minates 'ust a short distance above the bottom of t e vacuum chamber which is indicated at V. The-section 6 is extended up, wardl in the form of a pipe as indicated at 24 an this pipe extends upwardly into, the compression chamber and is bent as at 25 so as to discharge downwardly into the compression chamber. BThe body rtion 8 is formed with a recelvin port 1n line with the pipe 23 and a delivery port in line with the p1pe 24. Suitable connection may be made with the vacuum chamber at 26.

The pump casing 1 is formed in the port 27 which leads from the extreme lower part of the compression chamber. The casing is also provided with a port 28whh extends pump casing is closed by a cover.

into the vacuum chamber. A pipe 29 is suitably connected to the casing so that the port 27 is connected through this pipe with port28. l

The operation of 'my improved air pump is as follows: In the starting of the pump, a suitable 'quantity 'of oil may be placed 1n the vacuum chamber. This oil will be at. once drawn by the rotation of the pumping gears up through the pipe 23 and delivered by the pumping gears into the pipe 24, and from the pipe 24 into the compression chamber. As soon as the lower end of the pipe 23 is uncovered by the oil, then air is drawn into the pipe 23 by the rotating gears. A suiiicient quantity of oil is used so that the oil level is substantially on the line in Fig. 1 of the drawings. The oil in the compression chamber runs slowly back through the bypass pipe 29 into the vacuum chamber. The capacity of this pipe is relatively small compared with the capacity of the pump to deliver oil and air. As a result a small quantity of oil will be drawninto the ipe' 23 with the air, and thereby oil will be rought into contact with the inner wall of the pump chambers and thus the inner wall will be lubricated. The surplus oil will be carried along with the air over into the compression chamber and will pass back into the bypass thus completing the cycle. The preure in the compression chamber aids in forcing the oil back through the bya p Inasmuch as the air is delivered into the compression chamber at a point above the surface of the oil, there will be no foaming of the oil, and the oil in the air will readily separate therefrom and collect in the bottom of the chamber.

From the above it will be apparent that I have provided an air pump wherein the walls of the pumping chamber are very effectively lubricated by the lubricating oil` carried into the pumping chamber by the incoming air and wherein also the lubricating oil is collected and returned to the vacuum side of the pump where it may be again utilized for lubricating purposes.

It is obvious that minor changes in the details of construction and the arrangement of parts may be made without departing from the Spirit of the invention as set forth in the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters-Patenti, is Y 1. An' air pump including in combination, a pump casing having a central section dividing and separating the casing into a lower vacuum chamber and an upper compression chamber, said central section hav- Va cylindrical bore, a pump body fitting said bore and having pump chambers therem, passages respectively connecting the pump chambersswith the vacuum chamber and the compression chamber, rotating pump gears located in said pump chambers, means for supporting said pump gears, and means for closing the bore.

2. An air pump including in combination, a pump casing having a central section dividing and separating the casing into a lower-"vacuum chamber and an upper compression chamber, said central section having a cylindrical bore, a pump body itting sa1d bore and having pump chambers therein, passages respectively 'connecting the pump chambers with the vacuum chamber and the compression chamber, rotating pump gears locatedin said pump chambers, means or supporting said pump gears, means for closing the bore, and a bypass connecting the compression chamber with the vacuum chamber.` f

3. An air pump including Ain combination, a pump casing having a central integral section dividing and separating the casing into a lower vacuum chamber and an upper compression chamber, said central section having a cylindrical bore, a pump body tting said bore and having pump ,chambers therein, passages respectively connecting the pump chambers with the vacuum; chamber and compression chamber, rotating pump ears located in said pump chambers, means or supporting the gears, means for closing the cylindrical bore in the casing, ,and a bypass connecting the compression chamber with the vacuum chamber, said bypass being of considerable smaller capacity than the pumping capacity of the pumping gears whereby a relatively small amount of lubricating oil may be carried through with the air for lubricating the. pump. gears collected in the compression chamber and slowly returned to the vacuum chamber.

4:. An air pump including in combination a pump casin having a central section dividing the casing into a lower vacuum chamber and an upper compressori chamber, said central section having a cylindrical bore, a pump body fitting said bore and having pump chambers, rotating pumping gears locatedv in said pump chambers, a bearing plate at the inner end of said bore, and a face plate at the outer end of said bore for closing the same, said plates having bearings for supportin the pumping gears, and means whereby luricating oil is caused to pass through the pump chambers with the air, collect in the compression chamber and be returned to the vacuum chamber.

5. An air pump including in combination a pump casing having a central section dividing the casing into a lower vacuum chamber and an upper compression chamber, said central section having a cylindrical bore, a

`pump body fitting said bore 'and having pump chambers, rotating pumping gears located in said pump chambers, a bearing' plate at the inner end of said bore, and a face plate at the outer end of said bore for closing the same, said plates having bearings for supporting the pumping gears, a pipe connected with the pump chambers and eX- tending downwardly into the vacuum chamb er, and a 'bypass connecting the lower part of the compression chamber with the vacuum chamber.

6. An air pump including in combination a pump casin having a central section dividing the casing into a lower vacuum chamber and an upper compression chamber, said central section having a cylindrical bore, a pump body iitting said bore and having pump chambers, rotating pumping gears located in said pump chambers, a bearing plate at the inner end of said bore, and a face plate atthe outer end of said bore for closing the same, said plates having bearings for supporting the pumping gears, a pipe connected with the pump chambers and extending downwardly into' the vacuum chamber, a bypass connecting the lower part of the compression chamber with the vacuum chamber, and a pipe connected with said pump chambers and extending upwardly into said compression chamber, said pipe having its upper end bent so as to discharge downwardly into the compression chamber.

In testimony whereof, I aiix my signature.

CARL E. ANDERSON. 

